Recently, rechargeable secondary batteries are widely used as energy sources of wireless mobile devices.
In addition, the secondary battery has been prominent as a power source of an electric vehicle (EV), a hybrid electric vehicle (HEV), etc., which have been suggested as a scheme for solving air pollution from an existing gasoline vehicle, diesel vehicle, etc., using fossil fuel.
Small-sized mobile devices use one or more battery cells per one device. In contrast, middle and large-sized devices such as a vehicle, etc., use, as a unit battery, a middle and large-sized battery pack in which a plurality of battery cells are electrically interconnected, due to necessity of high output and large capacity.
The middle and large-sized battery pack is preferably manufactured with, if possible, small size and weight. Therefore, a square type battery, a pouch type battery, or the like, which can be stacked at high integration and have a small ratio of weight to capacitance, is mainly used as a battery cell of the middle and large-sized battery pack. Among them, particularly, the pouch type battery of which weight is small, an electrolyte is less likely to leak, and manufacturing cost is low, is attracting more interest.
A nickel-hydrogen secondary battery has been mostly used as a unit cell (battery cell) of the middle and large-sized battery pack. However, in recent, a lithium secondary battery providing a high ratio of output power to capacitance, like in a small-sized battery pack, is most studied, and some have reached commercialization.
However, the lithium secondary battery has a low stability problem, fundamentally. In particular, the electrode assembly for a secondary battery is problematic with safety thereof due to internal short circuits caused by motion of electrode plates, and a production process to prevent the internal short circuits is not easy.
Accordingly, an electrode assembly for a secondary battery, capable of preventing internal short circuits to improve stability and reliability, providing greater insertability into a pouch type battery case to improve stability and reliability, and growing productivity, is needed.
As described above, technology to prevent internal short circuits due to movement of electrode plates in the electrode assembly for a secondary battery has been known in the related art.
Korean Patent No. 1062681 (Jelly-Roll Type Secondary Battery Characterized by That Substantially Total of Active Material-Non-Coated Portion is Insulated) discloses a secondary battery where an insulation layer is provided on an end of an active-material-non-coated portion, to thereby suppress formation of dendrite and thus prevent breakage or short-circuiting of a separator, resulting in improving stability.